1. Field of Invention
This invention relates to a transparency mount for framing a short piece of a film strip, commonly a so called diapositive. More specifically the invention is concerned with a transparency mount of the kind comprising a generally square, frame-like base plate having a generally rectangular picture opening therein which is defined by two pairs of opposed frame members, at least one of said pairs of frame members forming on one side of the base plate and adjacent the picture opening therein seats for corresponding marginal portions of the transparency, said base plate having hingedly connected to opposite outer edges thereof flap-like covering members formed integrally with the base plate proper and being foldable inwardly from free inoperative positions, in which they extend generally outwards from their respective base plate edges, into locked operative positions, in which they are superposed over said one side of the base plate in a manner to overlap opposite marginal portions of the transparency seated thereon.
2. Description of the Prior Art
A wide variety of transparency mounts of various materials have been suggested in the prior art. Many of them are composed of two or more separate parts which are to be assembled into a coherent unit enclosing the transparency to be framed. This makes the framing operation fairly complex and is objectionable also because of comparatively high manufacturing and distribution costs. Therefore, early attempts were made to create transparency mounts in which one single piece of material was all that was needed and in which at least one portion of the piece could be folded over another portion thereof in order to complete the mount in the framing operation. In a first group of mounts of the lastmentioned kind there are only two generally similar frame-like portions of the piece to be folded together, one upon the other, while in a second group there are two or more flap-like portions to be folded in over a frame-like central portion.
Typical examples of relatively modern mounts of the first one of said lastmentioned groups are illustrated in e.g. the U.S. Pat. Nos. 3,200,527 and 3,281,976, while typical early forms of mounts of the second group are illustrated in e.g. the U.S. Pat. Nos. 2,227,986 and 2,352,243, a further, relatively modern form of mount of said second group being illustrated in the U.S. Pat. No. 3,466,780.
Transparency mounts belonging to the first one of the two groups referred to above, although having become more and more sophisticated during decades of development and improvement from a simple form of double-folded cardboard frame still used by certain film processors, are objectionable mainly for two reasons. They are fairly difficult to manufacture in plastic by injection molding, which is necessary in order to meet the demand for a reduced thickness of certain portions of the piece and an increased thickness of others, because of their almost doubled size in a folded-out position in which they have to be molded. In addition, certain difficulties are encountered in the framing operation, particularly if the transparency is not entirely flat, because complex manipulations are needed to keep it properly positioned when the one full frame portion is folded over the other.
On the other hand, the transparency mounts belonging to the second group in the various forms they have so far been presented also exhibit serious deficiencies. In the early form they have not less than four flap-like portions to be folded in over a central, frame-like one, which makes the mount unnecessarily extensive in its folded out condition and also renders the framing operation slow and inconvenient, while in the modern form the overall size of the folded out piece of material is again at least twice that of the completed mount and, in addition, of such an irregular and complex shape that it is easily damaged when handled. Also, the early form must be made of a pliant but substantially non-resilient material, such as sheet aluminum, in order to remain closed after folding and, hence, cannot be made from plastic as desirable, while the modern form relies on the use of adhesive for keeping the mount closed after completion and for making the mount sufficiently rigid in its completed condition, which makes it difficult to remove the framed transparency without damage and puts a reuse of the mount out of the question.